Methods, systems, and media for predicting sensor measurement quality

ABSTRACT

Methods, systems, and method for predicting sensor measurement quality. In some implementations, the method comprises: measuring, using a wearable computing device that includes a processor and a sensor, information indicating motion of the wearable computing device during a current time period; identifying one or more parameters associated with a determination of a likelihood that one or more measurements from the sensor configured within the wearable computing device is of sufficient quality for calculating a physiological metric using the one or more measurements from the sensor, wherein the one or more parameters include contextual parameters associated with the wearable computing device; determining the likelihood that the measurement from the sensor associated with the user device is of sufficient quality at a second time period for calculating the physiological metric using the measurement from the sensor based on the identified one or more parameters and based on the information indicating the motion of the user device during the current time period; in response to determining that the likelihood exceeds a predetermined threshold, activating the processor and the sensor and collecting a measurement from the sensor at the second time period; and updating the identified one or more parameters based on the motion of the user device during the current time period and based on the measurement from the sensor at the second time period.

TECHNICAL FIELD

The disclosed subject matter relates to methods, systems, and media forpredicting sensor measurement quality. More particularly, the disclosedsubject matter relates to analyzing, at a current time period, sensorinformation and/or contextual information associated with a wearablecomputing device to determine whether to obtain additional sensorinformation or perform analysis of such sensor information at asubsequent time period.

BACKGROUND

People are increasingly interested in using wearable computing devices,such as fitness trackers or smartwatches, to measure differentphysiological parameters, such as heart rate or heart rate variability.Measuring or determining a physiological parameter is often done basedon sensor readings, for example, using a photoplethysmographic sensor togenerate photoplethysmographic data (e.g., a photoplethysmographicwaveform) that can be used to calculate a physiological parameter, suchas heart rate or heart rate variability.

The performance of such a sensor used for determining a physiologicalparameter, however, is typically dependent on factors such as motion.For example, a sensor reading from a photoplethysmographic sensor maylack accuracy if the user is in motion. Nevertheless, many devices thatinclude these sensors typically make measurements at fixed intervals,regardless of whether the measurements are likely to be noisy or usefulfor calculating a physiological parameter, such as heart ratevariability. This can be resource intensive, for example, causing thedevice to unnecessarily consume power by waking up a processor that, inturn, activates one or more sensors to make sensor measurements that arenot of sufficient quality to be used in calculating the desiredphysiological parameter. Moreover, these collected sensor measurementsthat are not of sufficient quality are often discarded.

Accordingly, it is desirable to provide new methods, systems, and mediafor predicting sensor measurement quality.

SUMMARY

Methods, systems, and media for predicting sensor measurement qualityare provided.

In accordance with some implementations of the disclosed subject matter,a method for predicting sensor measurement quality is provided, themethod comprising: measuring, using a wearable computing device thatincludes a processor and a sensor, information indicating motion of thewearable computing device during a current time period; identifying oneor more parameters associated with a determination of a likelihood thatone or more measurements from the sensor configured within the wearablecomputing device is of sufficient quality for calculating aphysiological metric using the one or more measurements from the sensor;determining the likelihood that the measurement from the sensorassociated with the user device is of sufficient quality at a secondtime period for calculating the physiological metric using themeasurement from the sensor based on the identified one or moreparameters and based on the information indicating the motion of theuser device during the current time period; in response to determiningthat the likelihood exceeds a predetermined threshold, activating theprocessor and the sensor and collecting a measurement from the sensor atthe second time period; and updating the identified one or moreparameters based on the motion of the user device during the currenttime period and based on the measurement from the sensor at the secondtime period.

In some implementations, the sensor is a photoplethysmography sensor andthe physiological metric is heart rate variability of a user of thewearable computing device.

In some implementations, the method further comprises determiningcontextual information associated with the wearable computing device,wherein the likelihood that the measurement from the sensor is ofsufficient quality at the second time period for calculating thephysiological metric using the measurement from the sensor is based onthe identified one or more parameters, the information indicating themotion of the user device during the current time period, and thedetermined contextual information associated with the wearable computingdevice.

In some implementations, the one or more parameters include a thresholdassociated with the information indicating the motion of the user deviceduring the current time period, and the likelihood is determined basedon the threshold associated with information indicating the motion ofthe user device.

In some implementations, the information indicating the motion of theuser device includes an acceleration of the user device, and wherein thethreshold associated with the information indicating the motion of theuser device is a mean acceleration measured during the current timeperiod.

In some implementations, the parameters are determined based on atraining set comprising a plurality of training samples, wherein atraining sample from the plurality of training samples includes theinformation indicating the motion of the user device and a correspondingsensor measurement.

In some implementations, the method further comprises, in response todetermining that the likelihood does not exceed the predeterminedthreshold, causing the identified one or more parameters to be updatedand inhibiting the processor and the sensor of the wearable computingdevice from being activated.

In accordance with some implementations of the disclosed subject matter,a system for predicting sensor measurement quality is provided, thesystem comprising a sensor and a hardware processor connected to thesensor, wherein the hardware processor is configured to: measureinformation indicating motion of the wearable computing device during acurrent time period; identify one or more parameters associated with adetermination of a likelihood that one or more measurements from thesensor configured within the wearable computing device is of sufficientquality for calculating a physiological metric using the one or moremeasurements from the sensor; determine the likelihood that themeasurement from the sensor associated with the user device is ofsufficient quality at a second time period for calculating thephysiological metric using the measurement from the sensor based on theidentified one or more parameters and based on the informationindicating the motion of the user device during the current time period;in response to determining that the likelihood exceeds a predeterminedthreshold, activate the processor and the sensor and collect ameasurement from the sensor at the second time period; and update theidentified one or more parameters based on the motion of the user deviceduring the current time period and based on the measurement from thesensor at the second time period.

In accordance with some implementations of the disclosed subject matter,a non-transitory computer-readable medium containing computer executableinstructions that, when executed by a processor, cause the processor toperform a method for predicting sensor measurement quality is provided,the method comprising: measuring, using a wearable computing device thatincludes a processor and a sensor, information indicating motion of thewearable computing device during a current time period; identifying oneor more parameters associated with a determination of a likelihood thatone or more measurements from the sensor configured within the wearablecomputing device is of sufficient quality for calculating aphysiological metric using the one or more measurements from the sensor;determining the likelihood that the measurement from the sensorassociated with the user device is of sufficient quality at a secondtime period for calculating the physiological metric using themeasurement from the sensor based on the identified one or moreparameters and based on the information indicating the motion of theuser device during the current time period; in response to determiningthat the likelihood exceeds a predetermined threshold, activating theprocessor and the sensor and collecting a measurement from the sensor atthe second time period; and updating the identified one or moreparameters based on the motion of the user device during the currenttime period and based on the measurement from the sensor at the secondtime period.

In accordance with some implementations of the disclosed subject matter,a system for predicting sensor measurement quality is provided, thesystem comprising: means for measuring information indicating motion ofthe wearable computing device during a current time period; means foridentifying one or more parameters associated with a determination of alikelihood that one or more measurements from a sensor configured withinthe wearable computing device is of sufficient quality for calculating aphysiological metric using the one or more measurements from the sensor;means for determining the likelihood that the measurement from thesensor associated with the user device is of sufficient quality at asecond time period for calculating the physiological metric using themeasurement from the sensor based on the identified one or moreparameters and based on the information indicating the motion of theuser device during the current time period; in response to determiningthat the likelihood exceeds a predetermined threshold, means foractivating the processor and the sensor and means for collecting ameasurement from the sensor at the second time period; and means forupdating the identified one or more parameters based on the motion ofthe user device during the current time period and based on themeasurement from the sensor at the second time period.

BRIEF DESCRIPTION OF THE DRAWINGS

Various objects, features, and advantages of the disclosed subjectmatter can be more fully appreciated with reference to the followingdetailed description of the disclosed subject matter when considered inconnection with the following drawings, in which like reference numeralsidentify like elements.

FIG. 1 shows an example of a process for determining whether to make asensor measurement or otherwise obtain sensor information in accordancewith some implementations of the disclosed subject matter.

FIG. 2 shows an example of a process for determining parameters forpredicting a likelihood that a sensor measurement will be of sufficientquality in accordance with some implementations of the disclosed subjectmatter.

FIG. 3 shows a schematic diagram of an illustrative system suitable forimplementation of mechanisms described herein for determining whether tomake a sensor measurement in accordance with some implementations of thedisclosed subject matter.

FIG. 4 shows a detailed example of hardware that can be used in a serverand/or a user device of FIG. 3 in accordance with some implementationsof the disclosed subject matter.

DETAILED DESCRIPTION

In accordance with various implementations, mechanisms (which caninclude methods, systems, and media) for predicting sensor measurementquality are provided.

In some implementations, the mechanisms described herein can determine alikelihood that a sensor associated with a user device (e.g., a wearablecomputing device, such as a fitness tracker or smartwatch, etc.) willmake a measurement of relatively high quality and/or that is ofsufficient quality such that it can be used to calculate a particularmetric, such as a physiological parameter of a user of the user device.For example, in some implementations, the sensor can be aphotoplethysmograph (PPG) sensor configured on a wearable computingdevice in which the sensor can be used to measure or infer a heartbeatof a user of the wearable computing device. In some suchimplementations, the mechanisms can calculate a likelihood that areading from the PPG sensor will be of high enough quality to infer theheartbeat of the user, that the reading will be of high enough qualityto calculate a heart rate or heart rate variability (HRV) of the user,and/or calculate any other suitable metrics.

In some implementations, the mechanisms can calculate the likelihoodthat the sensor reading will be of sufficiently high quality based onany suitable information. For example, in some implementations, thelikelihood can be calculated based on motion data associated with theuser device that indicates acceleration of the user device over aparticular time window (e.g., ten seconds, and/or any other suitableduration of time). As another example, in some implementations, thelikelihood can be calculated based on contextual information associatedwith the user device, such as a time of day, ambient environmentalconditions (e.g., an amount of ambient light, an ambient temperature,and/or any other suitable environmental conditions), a current useractivity, and/or any other suitable contextual information.

In some implementations, the mechanisms described herein can train anysuitable algorithm that can be used to calculate the likelihood. Forexample, in some implementations, the mechanisms can train athresholding algorithm, a feature-based classifier, a neural network,and/or any other suitable type of algorithm, as described below in moredetail in connection with FIG. 2. In some implementations, themechanisms can construct training samples based on motion data,contextual data, and/or previous sensor readings to train an algorithm.In some implementations, the mechanisms can update the training samples,and, therefore, update the algorithm with new training samples overtime.

In some implementations, the mechanisms described herein can be used toallow a user device, such as a fitness tracker or a smartwatch, tooperate more efficiently by collecting sensor data only when acalculated likelihood indicates that the sensor reading is likely to beof sufficiently high quality. By not unnecessarily collecting sensorreadings and calculating metrics (e.g., heart rate, HRV, and/or anyother suitable metrics) in instances where the mechanisms determine thatthe sensor readings or resulting metrics are likely to be inaccurate ortoo noisy (e.g., a noise level greater than a particular thresholdvalue), the user device can reduce power consumption and save batterylife. For example, the mechanism can determine at which instances toactivate a processor and one or more sensors on a user device inresponse to determining that collected sensor readings would be ofsufficient quality (e.g., a quality score greater than a particularquality threshold).

Turning to FIG. 1, an example 100 of a process for determining whetherto collect a measurement from a sensor is shown in accordance with someimplementations of the disclosed subject matter. In someimplementations, blocks of process 100 can be implemented on anysuitable user device, such as a wearable computing device (e.g., afitness tracker, and/or any other suitable type of user device), amobile phone, and/or any other suitable type of user device.

Process 100 can begin by collecting data indicative of current motion ofthe user device at 102. In some implementations, process 100 can collectthe motion data in any suitable manner. For example, in someimplementations, process 100 can sample a motion sensor associated withthe user device, such as an accelerometer, a gyroscope, and/or any othersuitable type of motion sensor. In some implementations, process 100 cancollect data representing motion of the user device that spans anysuitable time range (e.g., ten milliseconds of motion data, one secondof motion data, and/or any other suitable time range). In someimplementations, the collected data can include any suitable number ofmeasurement samples.

Process 100 can determine contextual information associated with theuser device and/or a user of the user device at 104. In someimplementations, the contextual information can include informationabout an environment in which the user device is currently located. Forexample, in some implementations, the contextual information can includea current temperature (e.g., a current ambient temperature inside a roomthe user device is currently located, a current outside temperature fora geographic location in which the user device is currently located,and/or a current temperature for any other suitable location). Asanother example, in some implementations, the contextual information caninclude a current time of day, a current day of the week, a current timeof the year, and/or any other suitable timing information. As yetanother example, in some implementations, the contextual information caninclude an amount of light in a room the user device is currentlylocated in.

In some implementations, the contextual information can includeinformation about an activity that a user of the user device iscurrently participating in. For example, in some implementations, thecontextual information can indicate whether the user is currentlywatching television or otherwise consuming media content, sleeping,exercising (e.g., including a particular type of exercise), working at acomputer, and/or performing any other suitable type of activity. In someimplementations, contextual information indicating an activity that auser of the user device is participating in can be determined based onany suitable information. For example, in some implementations, process100 can determine the current activity based on explicit informationprovided by the user, such an indication via an interface or via aninput device on the user device that the user is starting a run, anindication that the user is going to sleep, and/or any other suitabletype of indication. As another example, in some implementations, process100 can infer the current activity based on any suitable information. Asa more particular example, in some implementations, process 100 candetermine that a user is likely to be working at a computer based onlocation information (e.g., based on Global Positioning Systemcoordinates, and/or any other suitable location information) indicatingthat the user is at work and motion data indicating that the user is notmoving around. As another more particular example, in someimplementations, process 100 can determine that a user is likely runningbased on location information or motion data indicating that the user iscurrently moving at a particular pace (e.g., a particular number ofmiles per hour, a particular number of steps per minute, and/or anyother suitable pace metric). As yet another particular example, in someimplementations, process 100 can determine that a user is likelysleeping based on motion data indicating that a user is not moving or isnot moving very much, ambient light information indicating that the userdevice is in a dark environment, and/or timing information indicatingthat a current time of day is between particular hours of the day (e.g.,between 10 p.m. and 6 a.m., and/or any other suitable hours).

At 106, process 100 can calculate a likelihood that a recording from asensor associated with the user device will be of relatively highquality and/or of sufficiently high quality for a particular calculationbased on the motion data and/or the contextual data. For example, insome implementations, process 100 can calculate a likelihood that asensor reading for a time period subsequent to the time period overwhich motion data was collected (as described above in connection withblock 102) will be of relatively high quality and/or of sufficientlyhigh quality for a particular calculation. In some implementations, thesensor can be any suitable type of sensor, such as a photoplethysmograph(PPG) sensor used for calculating a user's heart rate. In someimplementations, process 100 can calculate a likelihood that a recordingfrom the sensor will yield data of high enough quality to calculate aparticular metric. For example, in instances where the sensor is a PPGsensor, process 100 can calculate a likelihood that a recording from thePPG sensor will be of high enough quality to determine heartbeats of theuser, calculate a heart rate of the user, calculate an HRV of the user,calculate a respiration rate of the user, and/or any other suitablemetric. As a specific example, in instances where the user device is awearable computing device (e.g., a fitness tracker, a smartwatch, etc.)worn on a wrist or arm of a user and where the sensor is a PPG sensor,process 100 can calculate a likelihood that the wrist or the arm of theuser will remain still enough for a duration of a recording from the PPGsensor such that data from the recording from the PPG sensor can be usedto extract peaks corresponding to heartbeats of the user to determineheart rate and/or HRV. In continuing this example, process 100 cancalculate a likelihood that a recording from the PPG sensor will be atleast a given quality to determine a first type of metric (e.g., a heartrate of the user wearing the wearable computing device) but will not beat least a given quality to determine a second type of metric.

It should be noted that process 100 can determine the likelihood that arecording from the sensor will be of relatively high quality and/oruseful for a particular calculation using any suitable technique orcombination of techniques. For example, in some implementations, process100 can use the motion data collected at block 102 and the contextualdata received at block 104 as inputs to any suitable algorithm,calculation, or formula, to determine the likelihood. As a moreparticular example, in some implementations, process 100 can use anysuitable machine learning algorithm or technique(s), as described belowin more detail in connection with FIG. 2. In some implementations, amachine learning algorithm used by process 100 can be trained with anysuitable training samples, as described below in more detail inconnection with FIG. 2. In some implementations, process 100 candetermine more than one likelihood, such as a likelihood that datacollected from the sensor is of high enough quality to calculatedifferent metrics. For example, in some implementations, process 100 cancalculate a first likelihood that the sensor data will be of high enoughquality to calculate a heart rate, and a second likelihood that thesensor data will be of high enough quality to calculate an HRV.

At 108, process 100 can determine whether the calculated likelihoodexceeds a predetermined threshold (e.g., greater than 50%, greater than70%, greater than 90%, and/or any other suitable threshold).

If, at 108, process 100 determines that the calculated likelihood doesnot exceed the predetermined threshold (“no” at 108), process 100 canproceed to block 112, described in more detail below. That is, process100 can proceed to block 112 without making a measurement using thesensor. For example, process 100 can inhibit the processor of a wearablecomputing device and one or more sensors connected to the processor frombeing activated and from obtaining one or more sensor measurements.

If, at 108, process 100 determines that the calculated likelihoodexceeds the predetermined threshold (“yes” at 108), process 100 canproceed to block 110. At 110, process 100 can make a measurement usingthe sensor. For example, in instances where the sensor is a PPG sensor,process 100 can transmit any suitable instructions that cause alight-emitting diode associated with the PPG sensor to produce lightilluminating a patch of skin of a user of the user device and anysuitable instructions that cause a photodiode associated with the PPGsensor to measure an amount of light transmitted and/or reflected by theskin of the user. In another example, process 100 can activate aprocessor associated with a user device from a sleep mode to an activemode. In some implementations, any suitable number of measurementsamples can be received by process 100.

In some implementations, process 100 can calculate any suitable metricsusing the recorded data. For example, in instances where the sensor is aPPG sensor and process 100 recorded measurements of an amount of lightreflected and/or transmitted by the user's skin, process 100 cancalculate metrics such as an instantaneous heart rate of the user, anaverage heart rate for the user based on any suitable time period (anaverage over the last second, an average over the last two seconds,and/or any other suitable time period), an HRV of the user, arespiration rate of the user, and/or any other suitable metric.

At 112, process 100 can collect information that indicates an accuracyof the likelihood calculation. In instances where the calculatedlikelihood exceeded the predetermined threshold at block 108 and where asensor recording was made at block 110, process 100 can determine anaccuracy of the data recorded by the sensor and/or an accuracy of theone or more metrics calculated based on the sensor data. For example, ininstances where the sensor is a PPG sensor, process 100 can determine aconfidence level corresponding to one or more metrics calculated basedon the sensor data. As a more particular example, process 100 candetermine a confidence level in a heart rate and/or an HRV calculatedbased on the sensor data. As another more particular example, process100 can calculate a score indicating a quality of a metric calculatedbased on the sensor data, such as a score indicating a quality of aheart rate trace calculated based on the sensor data. As a specificexample, process 100 can calculate a quality score based on adetermination of an amount of noise in the heart rate trace, and/orbased on any other suitable information.

In instances where the calculated likelihood did not exceed thepredetermined threshold at block 108 and where block 110 was omitted,process 100 can collect any suitable information indicating the accuracyof the likelihood calculation. For example, in instances where thecalculated likelihood indicated that a sensor reading would likely be ofrelatively poor quality because of a likelihood of excessive motion ofthe user device, process 100 can determine whether the prediction ofexcessive motion occurred based on any suitable information (e.g.,information from a motion sensor, location information, and/or any othersuitable information).

Process 100 can then return back to 102.

Note that, in some implementations, the information indicating theaccuracy of the likelihood calculation can be used to update parametersused to determine the likelihood of high quality sensor readings forfuture predictions. For example, as described below in more detail inconnection with block 206 of FIG. 2, the information can be used tocreate additional training samples for an algorithm used to determinethe likelihood of high quality sensor readings.

Turning to FIG. 2, an example 200 of a process for determiningparameters for determining a likelihood that a sensor reading will be ofrelatively high quality is shown in accordance with some implementationsof the disclosed subject matter. In some implementations, blocks ofprocess 200 can be implemented on any suitable device. For example, insome implementations, blocks of process 200 can be implemented on a userdevice associated with the sensor reading, such as a wearable computingdevice (e.g., a fitness tracker, a smartwatch, and/or any other suitabletype of wearable computing device). As another example, in someimplementations, blocks of process 200 can be implemented on a server,such as a server that receives data from one or more user devices anduses the received data to select parameters for an algorithm or functionfor determining the likelihood that a sensor reading will be ofrelatively high quality.

Process 200 can begin by receiving motion data and/or contextual data at202. For example, in some implementations, the motion data can berecordings from a motion sensor (e.g., an accelerometer, a gyroscope,and/or any other suitable type of motion sensor) associated with a userdevice, as described above in connection with block 102 of FIG. 1. Asanother example, in some implementations, the contextual data can beinformation such as timing information (e.g., a current time of day, acurrent day of the week, and/or any other suitable timing information),environmental information (e.g., a current ambient light level, acurrent noise level, and/or any other suitable environmentalinformation), a current activity of the user, and/or any other suitablecontextual information, as described above in connection with block 104of FIG. 1.

In some implementations, the received motion data and the receivedcontextual data can be used as training samples by process 200. Forexample, in some implementations, the received motion data and/or thereceived contextual data can be paired with a score indicating a qualityof a sensor reading. As a more particular example, in someimplementations, motion data indicating motion of a user device (e.g.,from an accelerometer associated with the user device) can be pairedwith an indication of a noise level of the sensor reading. In some suchimplementations, the noise level of the sensor reading can be on anysuitable scale (e.g., a binary scale indicating whether the sensorreading was noisy or not, an average noise level, and/or any othersuitable scale). In some implementations, the score indicating thequality of the sensor reading can be assigned manually and/oralgorithmically. For example, a training sample can include theaccelerometer samples paired with a 0, indicating that the PPG sensorreadings from the corresponding time window were too noisy to be useful.As another specific example, a training sample can include theaccelerometer samples paired with an average noise level of the PPGsensor readings from the corresponding time window.

In some implementations, each training sample can include motion datasamples and sensor reading samples of any suitable duration. Forexample, in some implementations, a sliding window of a particularduration (e.g., five seconds, ten seconds, and/or any other suitableduration) can be used to create each training sample. As a moreparticular example, in an instance where the sensor reading correspondsto measurements from a PPG sensor associated with the user device, atraining sample can include ten seconds of accelerometer data pairedwith an indication of a quality of the PPG sensor readings from thecorresponding ten second window. In some implementations, acorresponding time window of sensor measurements can be a time windowsubsequent to the time window of the motion data measurements.Alternatively, in some implementations, a time window of the sensormeasurements can overlap the time window of the motion data measurementswith any suitable overlap duration.

Note that, in some implementations, the contextual information can beincluded in a training sample in any suitable manner. For example, insome implementations, a training sample can additionally include anindication of an amount of ambient light during a time windowcorresponding to the motion data and/or to the sensor readings. Asanother example, in some implementations, a training sample can includean indication of a time of day, an ambient temperature, a currentactivity of the user, and/or any other suitable contextual informationduring a time window corresponding to the motion data and/or to thesensor readings.

Note that, in instances where process 200 is performed by a server,process 200 can receive motion data, contextual data, and sensorreadings from any suitable number of user devices (e.g., one, ten,fifty, one hundred, and/or any other suitable number) to constructtraining samples based on multiple user devices.

At 204, process 200 can train or construct an algorithm using thetraining samples received and/or constructed as described above inconnection with block 202. In some implementations, process 200 can beany suitable type of algorithm. For example, in some implementations,process 200 can be a thresholding algorithm that determines a thresholdof motion (as indicated by the motion data) for which the sensor readingis likely to be of high enough quality to calculate any suitablemetrics. As a more particular example, in some implementations, process200 can construct a histogram based on the motion data. As a specificexample, a histogram can be generated of mean acceleration or mean jerkvalues over a time window of the motion data for each training sample.In some implementations, the data points used to construct the histogramcan be tagged or labeled based on the score indicating a quality of thesensor reading for each training sample, as described above inconnection with block 202.

As another example, in some implementations, process 200 can train afeature-based classifier using the training samples. In someimplementations, the feature-based classifier can be any suitable typeof classifier, such as a neural network, a random forest algorithm, asupport vector machine, a logistic regression, and/or any other suitabletype of classifier. In some implementations, process 200 can constructfeatures using the motion data and/or the contextual data in anysuitable manner. For example, in some implementations, for each trainingsample, process 200 can construct features using means and/or standarddeviations of data samples corresponding to motion data for a particulartraining sample. As a more particular example, in some implementations,in instances where the motion data includes accelerometer readings overa ten second window, process 200 can construct features that include amean acceleration over the ten second window, a standard deviation ofthe accelerometer measurements over the ten second window, and/or anyother suitable features. In some implementations, each training samplecan be associated with any suitable number of features. For example, inan instance where motion data associated with a training sample includesaccelerometer data from a particular time window, process 200 canconstruct a group of features for the training sample that includes: afirst mean corresponding to a mean acceleration for a first third of theparticular time window, a first standard deviation corresponding to astandard deviation for the first third of the particular time window, asecond mean corresponding to a mean acceleration for a second third ofthe particular time window, a second standard deviation corresponding toa standard deviation for the second third of the particular time window,a third mean corresponding to a mean acceleration for a last third ofthe particular time window, a third standard deviation corresponding toa standard deviation for a last third of the particular time window,and/or any other suitable features. Note that, in some implementations,process 200 can construct features based on the contextual data in anysuitable manner. For example, in some implementations, process 200 canconstruct features that indicate timing information, ambientenvironmental information, and/or any other suitable features.

As yet another example, in some implementations, process 200 can train aconvolutional neural network or a deep neural network model. In somesuch implementations, the neural network can use raw motion data astraining samples. For example, in some implementations, a trainingsample can include raw accelerometer data from any suitable temporalwindow (e.g., ten seconds, and/or any other suitable duration of time).Additionally or alternatively, in some implementations, the neuralnetwork can use any other suitable data in training samples, such asdata indicating a user's activities, data indicating ambient light, dataindicating ambient temperature, a timing information, and/or any othersuitable contextual information.

At 206, process 200 can select parameters for calculating a likelihoodthat a sensor reading is likely to be of relatively high quality and/orof high enough quality to calculate a particular metric. For example, insome implementations, in instances where the algorithm used (asdescribed above in connection with block 204) is a thresholdingalgorithm, process 200 can select a threshold that, when applied to themotion data and/or contextual data, is likely to be associated with asensor reading of acceptable quality. As a more particular example,process 200 can determine a threshold for a mean acceleration over aparticular time period for which more than a predetermined percentage ofsensor readings made in a subsequent time period (e.g., greater than70%, greater than 90%, and/or any other suitable percentage) were ofacceptable quality. As a specific example, process 200 can determinethat more than 90% of sensor readings were of relatively high quality ifthe mean acceleration over a particular time window was less than apredetermined threshold. As another more particular example, process 200can determine a threshold for a mean acceleration over a particular timeperiod for which less than a predetermined percentage of sensor readingsmade in a subsequent time period (e.g., less than 20%, less than 10%,and/or any other suitable percentage) were of poor quality. As aspecific example, process 200 can determine that more than 10% of sensorreadings were of relatively poor quality if the mean acceleration overthe particular time window exceeds a predetermined threshold. As anotherexample, in instances where the algorithm used (as described above inconnection with block 204) is a feature-based classifier and/or a neuralnetwork, process 200 can identify weights or other parameters convergedon by the algorithm during training. As a more particular example, insome implementations, in instances where the algorithm used is a neuralnetwork, process 200 can identify weights for the neural networkconverged upon during an optimization of the weights, and/or identifiedin any other suitable manner.

In some implementations, the parameters identified by process 200 atblock 206 can be used by process 100 to determine a likelihood that asensor reading from a sensor associated with a user device (e.g., a PPGsensor, and/or any other suitable type of sensor) will record data ofrelatively high quality and/or of sufficient quality to calculate aparticular metric (e.g., heart rate, HRV, and/or any other suitablemetric) based on motion data and/or contextual data associated with theuser device, as described above in connection with block 106 of FIG. 1.For example, in instances where the algorithm used is a thresholdingalgorithm and the parameters identified at block 206 include a thresholdof acceleration for which more than a predetermined percentage of sensorreadings were of relatively high quality, process 100 can determinewhether a mean acceleration of acceleration data over a particular timewindow exceeds the threshold. As another example, in instances where thealgorithm used is a neural network and the parameters identified atblock 206 include weights for the neural network, process 100 can applythe weights to recorded motion data inputs and/or to contextual data topredict a likelihood that sensor readings for an subsequent time windowwill be of relatively high quality and/or of sufficient quality tocalculate a particular metric.

Process 200 can, in some implementations, return to block 202 andreceive additional motion data, contextual data, and sensor readings.Process 200 can then use the received data to construct additionaltraining samples to update parameters for calculating the likelihoodthat a sensor reading will be usable.

Turning to FIG. 3, an example 300 of hardware for determining whether tocollect sensor measurements that can be used in accordance with someimplementations of the disclosed subject matter is shown. Asillustrated, hardware 300 can include a server 302, a communicationnetwork 304, and/or one or more user devices 306, such as user devices308 and 310.

Server 302 can be any suitable server(s) for storing data and performingcalculations. For example, in some implementations, server 302 canreceive data from any suitable number of user devices that indicatemotion of the user devices, contextual information associated with theuser devices, and/or sensor readings from the user devices. In someimplementations, server 302 can use the data to train any suitablealgorithm for determining whether a sensor reading (e.g., from a PPGsensor, and/or any other suitable type of sensor) will produce data ofhigh enough quality to perform a particular measurement, as describedabove in connection with FIG. 2. In some implementations, server 302 canbe omitted.

Communication network 304 can be any suitable combination of one or morewired and/or wireless networks in some implementations. For example,communication network 304 can include any one or more of the Internet,an intranet, a wide-area network (WAN), a local-area network (LAN), awireless network, a digital subscriber line (DSL) network, a frame relaynetwork, an asynchronous transfer mode (ATM) network, a virtual privatenetwork (VPN), and/or any other suitable communication network. Userdevices 306 can be connected by one or more communications links (e.g.,communications links 312) to communication network 304 that can belinked via one or more communications links (e.g., communications links314) to server 302. The communications links can be any communicationslinks suitable for communicating data among user devices 306 and server302 such as network links, dial-up links, wireless links, hard-wiredlinks, any other suitable communications links, or any suitablecombination of such links.

User devices 306 can include any one or more user devices suitable forreceiving motion data indication a motion of the user device, receivingreadings from a sensor associated with the user device (e.g., a PPGsensor, and/or any other suitable type of sensor), determining whether areading from the sensor is likely to yield relatively high quality data,and/or for performing any other suitable functions. For example, in someimplementations, user devices 306 can include a wearable computingdevice, such as a fitness tracker, a smartwatch, and/or any othersuitable type of user device. As another example, in someimplementations, user devices 306 can include any other suitable type ofuser device, such as a mobile phone, a tablet computer, a laptopcomputer, a desktop computer, and/or any other suitable type of userdevice.

Although server 302 is illustrated as one device, the functionsperformed by server 302 can be performed using any suitable number ofdevices in some implementations. For example, in some implementations,multiple devices can be used to implement the functions performed byserver 302.

Although two user devices 308 and 310 are shown in FIG. 3 to avoidover-complicating the figure, any suitable number of user devices,and/or any suitable types of user devices, can be used in someimplementations.

Server 302 and user devices 306 can be implemented using any suitablehardware in some implementations. For example, in some implementations,devices 302 and 306 can be implemented using any suitable generalpurpose computer or special purpose computer. For example, a wearablecomputing device may be implemented using a special purpose computer.Any such general purpose computer or special purpose computer caninclude any suitable hardware. For example, as illustrated in examplehardware 400 of FIG. 4, such hardware can include hardware processor402, memory and/or storage 404, an input device controller 406, an inputdevice 408, display/audio drivers 410, display and audio outputcircuitry 412, communication interface(s) 414, an antenna 416, and a bus418.

Hardware processor 402 can include any suitable hardware processor, suchas a microprocessor, a micro-controller, digital signal processor(s),dedicated logic, and/or any other suitable circuitry for controlling thefunctioning of a general purpose computer or a special purpose computerin some implementations. In some implementations, hardware processor 402can be controlled by a server program stored in memory and/or storage404 of a server, such as server 302 as shown in and described above inconnection with FIG. 3. For example, the server program can causehardware processor 402 to train an algorithm for determining alikelihood a sensor reading from a user device is likely to be ofrelatively high quality, as described above in connection with FIG. 2.In some implementations, hardware processor 402 can be controlled by acomputer program stored in memory and/or storage 404 of a user device.For example, the computer program can cause hardware processor 402 todetermine a likelihood that a measurement from a sensor will be of highquality as described above in connection with FIGS. 1 and 2, and/orperform any other suitable actions.

Memory and/or storage 404 can be any suitable memory and/or storage forstoring programs, data, media content, and/or any other suitableinformation in some implementations. For example, memory and/or storage404 can include random access memory, read-only memory, flash memory,hard disk storage, optical media, and/or any other suitable memory.

Input device controller 406 can be any suitable circuitry forcontrolling and receiving input from one or more input devices 408 insome implementations. For example, input device controller 406 can becircuitry for receiving input from a touchscreen, from a keyboard, froma mouse, from one or more buttons, from a voice recognition circuit,from a microphone, from a camera, from an optical sensor, from anaccelerometer, from a gyroscope, from a temperature sensor, from a nearfield sensor, from a light sensor, and/or any other type of inputdevice.

Display/audio drivers 410 can be any suitable circuitry for controllingand driving output to one or more display/audio output devices 412 insome implementations. For example, display/audio drivers 410 can becircuitry for driving a touchscreen, a flat-panel display, a cathode raytube display, a projector, a speaker or speakers, and/or any othersuitable display and/or presentation devices.

Communication interface(s) 414 can be any suitable circuitry forinterfacing with one or more communication networks (e.g., communicationnetwork 304). For example, interface(s) 414 can include networkinterface card circuitry, wireless communication circuitry, and/or anyother suitable type of communication network circuitry.

Antenna 416 can be any suitable one or more antennas for wirelesslycommunicating with a communication network (e.g., communication network304) in some implementations. In some implementations, antenna 416 canbe omitted.

Bus 418 can be any suitable mechanism for communicating between two ormore components 402, 404, 406, 410, and 414 in some implementations.

Any other suitable components can be included in hardware 400 inaccordance with some implementations.

In some implementations, at least some of the above described blocks ofthe processes of FIGS. 1 and 2 can be executed or performed in any orderor sequence not limited to the order and sequence shown in and describedin connection with the figures. Also, some of the above blocks of FIGS.1 and 2 can be executed or performed substantially simultaneously whereappropriate or in parallel to reduce latency and processing times.Additionally or alternatively, some of the above described blocks of theprocesses of FIGS. 1 and 2 can be omitted.

In some implementations, any suitable computer readable media can beused for storing instructions for performing the functions and/orprocesses herein. For example, in some implementations, computerreadable media can be transitory or non-transitory. For example,non-transitory computer readable media can include media such asnon-transitory forms of magnetic media (such as hard disks, floppydisks, and/or any other suitable magnetic media), non-transitory formsof optical media (such as compact discs, digital video discs, Blu-raydiscs, and/or any other suitable optical media), non-transitory forms ofsemiconductor media (such as flash memory, electrically programmableread-only memory (EPROM), electrically erasable programmable read-onlymemory (EEPROM), and/or any other suitable semiconductor media), anysuitable media that is not fleeting or devoid of any semblance ofpermanence during transmission, and/or any suitable tangible media. Asanother example, transitory computer readable media can include signalson networks, in wires, conductors, optical fibers, circuits, anysuitable media that is fleeting and devoid of any semblance ofpermanence during transmission, and/or any suitable intangible media.

In situations in which the systems described herein collect personalinformation about users, or make use of personal information, the usersmay be provided with an opportunity to control whether programs orfeatures collect user information (e.g., information about a user'ssocial network, social actions or activities, profession, a user'spreferences, or a user's current location). In addition, certain datamay be treated in one or more ways before it is stored or used, so thatpersonal information is removed. For example, a user's identity may betreated so that no personally identifiable information can be determinedfor the user, or a user's geographic location may be generalized wherelocation information is obtained (such as to a city, ZIP code, or statelevel), so that a particular location of a user cannot be determined.Thus, the user may have control over how information is collected aboutthe user and used by a content server.

Accordingly, methods, systems, and media for predicting sensormeasurement quality are provided.

Although the invention has been described and illustrated in theforegoing illustrative implementations, it is understood that thepresent disclosure has been made only by way of example, and thatnumerous changes in the details of implementation of the invention canbe made without departing from the spirit and scope of the invention,which is limited only by the claims that follow. Features of thedisclosed implementations can be combined and rearranged in variousways.

What is claimed is:
 1. A method for predicting sensor measurementquality, the method comprising: measuring, using a wearable computingdevice that includes a processor and a sensor, information indicatingmotion of the wearable computing device during a current time period;identifying one or more parameters associated with a determination of alikelihood that one or more measurements from the sensor configuredwithin the wearable computing device is of sufficient quality forcalculating a physiological metric using the one or more measurementsfrom the sensor; determining the likelihood that the measurement fromthe sensor associated with the user device is of sufficient quality at asecond time period for calculating the physiological metric using themeasurement from the sensor based on the identified one or moreparameters and based on the information indicating the motion of theuser device during the current time period; in response to determiningthat the likelihood exceeds a predetermined threshold, activating theprocessor and the sensor and collecting a measurement from the sensor atthe second time period; and updating the identified one or moreparameters based on the motion of the user device during the currenttime period and based on the measurement from the sensor at the secondtime period.
 2. The method of claim 1, wherein the sensor is aphotoplethysmography sensor and wherein the physiological metric isheart rate variability of a user of the wearable computing device. 3.The method of claim 1, further comprising determining contextualinformation associated with the wearable computing device, wherein thelikelihood that the measurement from the sensor is of sufficient qualityat the second time period for calculating the physiological metric usingthe measurement from the sensor is based on the identified one or moreparameters, the information indicating the motion of the user deviceduring the current time period, and the determined contextualinformation associated with the wearable computing device.
 4. The methodof claim 1, wherein the one or more parameters include a thresholdassociated with the information indicating the motion of the user deviceduring the current time period, and wherein the likelihood is determinedbased on the threshold associated with information indicating the motionof the user device.
 5. The method of claim 4, wherein the informationindicating the motion of the user device includes an acceleration of theuser device, and wherein the threshold associated with the informationindicating the motion of the user device is a mean acceleration measuredduring the current time period.
 6. The method of claim 1, wherein theparameters are determined based on a training set comprising a pluralityof training samples, wherein a training sample from the plurality oftraining samples includes the information indicating the motion of theuser device and a corresponding sensor measurement.
 7. The method ofclaim 1, further comprising, in response to determining that thelikelihood does not exceed the predetermined threshold, causing theidentified one or more parameters to be updated and inhibiting theprocessor and the sensor of the wearable computing device from beingactivated.
 8. A system for predicting sensor measurement quality, thesystem comprising: a sensor; and a hardware processor connected to thesensor, wherein the hardware processor is configured to: measureinformation indicating motion of the wearable computing device during acurrent time period; identify one or more parameters associated with adetermination of a likelihood that one or more measurements from thesensor configured within the wearable computing device is of sufficientquality for calculating a physiological metric using the one or moremeasurements from the sensor, wherein the one or more parameters includecontextual parameters associated with the wearable computing device;determine the likelihood that the measurement from the sensor associatedwith the user device is of sufficient quality at a second time periodfor calculating the physiological metric using the measurement from thesensor based on the identified one or more parameters and based on theinformation indicating the motion of the user device during the currenttime period; in response to determining that the likelihood exceeds apredetermined threshold, activate the processor and the sensor andcollecting a measurement from the sensor at the second time period; andupdate the identified one or more parameters based on the motion of theuser device during the current time period and based on the measurementfrom the sensor at the second time period.
 9. The system of claim 8,wherein the sensor is a photoplethysmography sensor and wherein thephysiological metric is heart rate variability of a user of the wearablecomputing device.
 10. The system of claim 8, wherein the hardwareprocessor is further configured to determine contextual informationassociated with the wearable computing device, wherein the likelihoodthat the measurement from the sensor is of sufficient quality at thesecond time period for calculating the physiological metric using themeasurement from the sensor is based on the identified one or moreparameters, the information indicating the motion of the user deviceduring the current time period, and the determined contextualinformation associated with the wearable computing device.
 11. Thesystem of claim 8, wherein the one or more parameters include athreshold associated with the information indicating the motion of theuser device during the current time period, and wherein the likelihoodis determined based on the threshold associated with informationindicating the motion of the user device.
 12. The system of claim 11,wherein the information indicating the motion of the user deviceincludes an acceleration of the user device, and wherein the thresholdassociated with the information indicating the motion of the user deviceis a mean acceleration measured during the current time period.
 13. Thesystem of claim 8, wherein the parameters are determined based on atraining set comprising a plurality of training samples, wherein atraining sample from the plurality of training samples includes theinformation indicating the motion of the user device and a correspondingsensor measurement.
 14. The system of claim 8, wherein the hardwareprocessor is further configured to, in response to determining that thelikelihood does not exceed the predetermined threshold, cause theidentified one or more parameters to be updated and inhibit theprocessor and the sensor of the wearable computing device from beingactivated.
 15. A non-transitory computer-readable medium containingcomputer executable instructions that, when executed by a processor,cause the processor to perform a method for predicting sensormeasurement quality, the method comprising: measuring, using a wearablecomputing device that includes a processor and a sensor, informationindicating motion of the wearable computing device during a current timeperiod; identifying one or more parameters associated with adetermination of a likelihood that one or more measurements from thesensor configured within the wearable computing device is of sufficientquality for calculating a physiological metric using the one or moremeasurements from the sensor, wherein the one or more parameters includecontextual parameters associated with the wearable computing device;determining the likelihood that the measurement from the sensorassociated with the user device is of sufficient quality at a secondtime period for calculating the physiological metric using themeasurement from the sensor based on the identified one or moreparameters and based on the information indicating the motion of theuser device during the current time period; in response to determiningthat the likelihood exceeds a predetermined threshold, activating theprocessor and the sensor and collecting a measurement from the sensor atthe second time period; and updating the identified one or moreparameters based on the motion of the user device during the currenttime period and based on the measurement from the sensor at the secondtime period.
 16. The non-transitory computer-readable medium of claim15, wherein the sensor is a photoplethysmography sensor and wherein thephysiological metric is heart rate variability of a user of the wearablecomputing device.
 17. The non-transitory computer-readable medium ofclaim 15, wherein the method further comprises determining contextualinformation associated with the wearable computing device, wherein thelikelihood that the measurement from the sensor is of sufficient qualityat the second time period for calculating the physiological metric usingthe measurement from the sensor is based on the identified one or moreparameters, the information indicating the motion of the user deviceduring the current time period, and the determined contextualinformation associated with the wearable computing device.
 18. Thenon-transitory computer-readable medium of claim 15, wherein the one ormore parameters include a threshold associated with the informationindicating the motion of the user device during the current time period,and wherein the likelihood is determined based on the thresholdassociated with information indicating the motion of the user device.19. The non-transitory computer-readable medium of claim 18, wherein theinformation indicating the motion of the user device includes anacceleration of the user device, and wherein the threshold associatedwith the information indicating the motion of the user device is a meanacceleration measured during the current time period.
 20. Thenon-transitory computer-readable medium of claim 15, wherein theparameters are determined based on a training set comprising a pluralityof training samples, wherein a training sample from the plurality oftraining samples includes the information indicating the motion of theuser device and a corresponding sensor measurement.
 21. Thenon-transitory computer-readable medium of claim 15, wherein the methodfurther comprises, in response to determining that the likelihood doesnot exceed the predetermined threshold, causing the identified one ormore parameters to be updated and inhibiting the processor and thesensor of the wearable computing device from being activated.